import java.io.*;
import java.util.*;
 
 
public class hack40Q1
{
   public static void main(String[] args) 
   {
      FastScanner obj = new FastScanner();
      out = new PrintWriter(new BufferedOutputStream(System.out));
      
      int[] arr=new int[26];
      for(int i=0;i<26;i++)
      	arr[i]=obj.nextInt(); 	
      
      String str=obj.next();
      int max=0;
      for(int i=0;i<str.length();i++)
      {
      	char c=str.charAt(i);
      	if(max<arr[c-'a'])
      		max=arr[c-'a'];
      
      }
      out.println(max*str.length());
      
      out.close();
   }

  
   //-----------PrintWriter for faster output---------------------------------
	public static PrintWriter out;
      
   //-----------FastScanner class for faster input----------
    public static class FastScanner 
    {
	 	   BufferedReader br;
	       StringTokenizer st;
	 
	    public FastScanner() {
	 	    br = new BufferedReader(new InputStreamReader(System.in));
	    }
	 
	   	String next() {
	  	    while (st == null || !st.hasMoreElements()) {
	    	    try {
	        	    st = new StringTokenizer(br.readLine());
	              } 
	            catch (IOException e) {
	       	  	    e.printStackTrace();
	              }
	          }
	     	return st.nextToken();
	      }
	 
	   	int nextInt() {
	   	    return Integer.parseInt(next());
	      }
	 
	   	long nextLong() {
	        return Long.parseLong(next());
	      }
	 
	    double nextDouble() {
	       	return Double.parseDouble(next());
	      }
	 
	    String nextLine()
	    {
	   	   String str = "";
			try {
				str = br.readLine();
			  } 
			catch (IOException e) {
				e.printStackTrace();
			  }
			return str;
	     }
	}
	   //--------------------------------------------------------
}